The present invention relates to radio communications. More specifically, it relates to a portable radio communication device that provides communications in a telephony mode and in a radio dispatch mode.
Recently, telephony communications and radio dispatch communications have been provided in a single portable communications device. For example, communications in the frequency bands that the Specialized Mobile Radio (SMR) industry utilizes now provide a user with the ability to communicate with a dispatcher in a radio dispatch mode as well as the ability to communicate over a PSTN link in a telephony mode.
Normally, a user of a portable communication device will communicate in a telephony mode by using the communication device just as a telephone would be used. That is, the microphone in the communication device is placed next to the user's mouth and the receiver or speaker in the communication device is placed next to the user's ear. The speaker need only be capable of broadcasting a low power audio signal, since the user's ear is next to the speaker. Conversely, when a portable communication device is used in a radio dispatch mode, the device is usually either held in a user's belt or is held in front of the user's face so that the speaker is not next to the user's ear. As a result, a dispatch speaker must be capable of providing a higher power audio signal.
Portable communication devices using a single speaker have been suggested to provide communications in a radio dispatch mode and in a telephony mode. See, for example, the portable radio, model number Viking CX, manufactured by E. F. Johnson. See, also, U.S. Pat. No. 5,276,916, issued to Pawlish. These devices, however, do not allow a user to communicate in the dispatch mode in the normal way. All of these devices also suffer from the drawback of attempting to provide diverse operational capabilities--one requiring a low audio signal and the other requiring a high audio signal--using a single speaker. Other approaches have been suggested. For example, a communication device having two speakers on the same side of the portable communication device is disclosed in U.S. Pat. No. 5,448,620, issued to Gershkovich.
Accordingly, new communication devices for providing improved telephony and radio dispatch communications are needed.